A car seat in which a seat cushion has recesses provided at a rear region of an upper side thereof such that arms (fix arms) provided at a rear side of a child seat and protruding rearward are insertable in the recesses so that attachment of the child seat to the vehicle seat is facilitated is hitherto known in the art (Patent Document 1). In this car seat, the seat cushion includes an outer covering with which a seat cushion pad of the seat cushion is covered, and the outer covering has slits provided in positions corresponding to the recesses, and the outer covering provided around the recesses is configured to extend over the recesses in an unsupported manner. Also disclosed in the Patent Document 1 as a conventional art is a particular configuration in which an outer covering is provided to extend along the side surfaces of the recesses while the bottom surfaces of the recesses are left uncovered.